1. Field of the Invention
The present invention resides in the field of photographic processing systems, and more particularly relates to a method and apparatus for splicing photographic films onto a common roll or core which is to be developed in a photographic processing machine.
2. Background
Film processing systems and, in particular, film splicing and desplicing machines, are known in the art. Such machines are commonly used in central film laboratories to achieve efficiencies in film development and processing operations. A plurality of rolls of film can be developed more efficiently by splicing together the film on a common roll, developing the film, and then desplicing the film to separate it into the original rolls, as compared with processing the rolls separately. Splicing machines and processes are particularly useful with Advanced Photo System (APS) film. With APS film, the film is removed from each cartridge and spliced with other rolls of film for development. After being developed, the web of film is despliced and a continuous set of negatives is reinserted in each corresponding cartridge. Thus, APS film customarily is processed in a manner different from 135 film (for which the film process usually involves cutting the negatives in strips and returning the cut negatives to the customer); with APS film, the negatives are returned as a continuous roll inside the original film cartridge. Splicing and desplicing operations are important steps in the processing of APS film, but certain problems are prevalent in conventional splicing processes. The tendency of the film tail to curl has resulted in a problem of film xe2x80x9cfoldover,xe2x80x9d as explained below, which has not heretofore been adequately resolved.
In a splicing operation, a trailing end of a first film is spliced to a leading end of a second film. A typical arrangement is shown in FIG. 6, where the trailing end 82 of the first film 80 is spliced to the leading end 86 of the second film 84 using a splice tape 88. FIG. 7 is a cross-sectional view of a splicing operation including a reciprocating splice head 90 which is lowered to fix the splice tape 88 over the trailing end of the film 80 and the leading end of the film 84. As shown in FIG. 7, the trailing end 82 of the film 80, which was previously wound tightly around the core of a film cartridge, tends to retain some curl at its end thereof. When the splice head 90 is lowered to apply the splice tape 88, any portion of the film 80 positioned under the splice head becomes part of the splice. Accordingly, if the trailing edge 82 of the film 80 exhibits some curl, this curved tail portion becomes sandwiched in the splice. In FIG. 7, the film 80 has been spliced in the folded condition, resulting in an added splice thickness in the region of the fold and thus film xe2x80x9cfoldover.xe2x80x9d This added thickness is undesirable and creates a pressure mark on successive wraps of the film wound onto a reel or core. The pressure mark is detrimental to other operations in the film developing process, for example showing up on negatives as a visible mark in the image area after developing. The pressure mark will also be visible on any prints made from the negative.
Previous attempts to solve the above-described problem involved use of the following implements: (1) an airjet, or (2) a mechanical element to bend back the film. Air jets are very expensive and difficult to maintain because tight tolerances are required. The aerodynamic effects of the air stream and the angle at which the air stream is positioned are important factors which, if not provided almost exactly in accordance with film feed requirements, can result in the film strip eluding the air stream, thus rendering the airjet useless. Mechanical xe2x80x9cbendingxe2x80x9d elements can cause significant damage to the surface of the film by, for example, causing the film surface to abrade or the emulsion to crack or break off. Further, such mechanical elements are not always effective in xe2x80x9ccatchingxe2x80x9d the curled tail section of the film.
U.S. Pat. No. 5,656,125 (""125 patent) discloses a film splicer including a reciprocating head 34 opposed by a pad 36, where films 12 are conveyed therebetween, and the head 34 is lowered to fix a splicing tape 39 to the films 12. The ""125 patent is directed to the problem of the splicing tape tending to adhere to the pad during a splicing operation. As shown in FIG. 1 of the ""125 patent, e.g., a concave portion 38 is cut in the pad 36 so as to avoid contact between the tape 39 and the pad 36 during splicing. The ""125 patent does not address the film xe2x80x9cfoldoverxe2x80x9d problem described herein.
We have found that an improved splice can be formed between photographic films substantially without resulting in film xe2x80x9cfoldoverxe2x80x9d or causing the formation of damaging pressure marks. An apparatus and method of forming a splice according to the present invention includes a movable anvil plate (i.e. splice pad) which clamps two film strips to a film track element where a splice is to be formed, thereby straightening any curl in the film and providing a surface to receive a splice head. The film track element provides support to the edges of the films from above and thus eliminates some curl or foldover. A cylinder then actuates the splice pad and moves the splice pad toward the film track element to clamp the films therebetween for receiving the splice head. A separate splice head cylinder is actuated, advancing the splice head downward toward the splice pad to form a splice. In a preferred embodiment, the splice head continues moving downward to force the splice pad down toward its rest position. The splice head preferably engages with the splice head for a sufficient time to adhere a splice tape to the two film strips.